I charged my phone (with the phone turned off) to an indicated 100%. But, when I turned it on, it indicated only 31%. It took nearly 4 hours to charge to this level. My battery didn't appear to be overheated.
Tried removing the battery (30 seconds), and restarted the phone, but charging is still problematic.
Currently, I'm charging with all the radio's turned off (gps, wireless, bluetooth), no usage, no streaming, nothing. Took about an hour and a half to get from 21% to 41%.
Could be software, could be a bad charger, could be a Bad battery.. Its hard to say but your charging it correctly with the phone off that is how I've charged all my smart phones and the many other cell phones down through the years.!
Just for the asking are using the charger that came with the phone the OEM box charger & cable it's always best to use these three together..